Mercer Valve Pressure Relief Valve 81-12151P18G11

During the visual inspection, the pressure relief valve is checked for any potential issues that may restrict the operation of the valve.; This inspection will be performed with the valve still assembled but the valve should not be pressurized for the safety of the person performing the inspection.

Corrosion and damage to the valve are some of the common problems found in the visual inspection.; Some of the items that should be checked in the visual inspection are as follows: • Cap and Seal Wire - The valve cap and seal wire should be checked first on all inspections.

These parts prevent adjustment tampering.; On the seal wire there is a pressed security seal that has an impression on it to indicate the certified company that last adjusted the set point of the valve.; When this seal wire is cut or removed, it indicates that someone may have adjusted the set point or altered the valve.; This voids any warranty the valve had.

• Flanges Connections - The flanges should be checked for wear, such as pitting, and any reduction in width that would cause improper sealing and reduction in pressure rating.

Proper fastening should also be checked.

• Threaded Connection - The threads on the threaded connections should be checked for any damage that could potentially compromise the sealing of the threads or the strength of the connection.

• Outlet - The valve's outlet should be inspected to make sure there is not any corrosion or other debris accumulation within that could inhibit the operation of the valve.

• External Surface - The valve should be checked for any damage that has occurred that could restrict or impair the operation of the valve.

Tubing lines, bent piping, and other external attachments are commonly damaged and can cause unfitting function.

The following general procedure is recommended for the disassembling of a Mercer 8100 Series PRV.; Non-standard, “special”, configurations are possible and these instructions may not be reflective of them; a special configuration is indicated by a special code at the end of the PRV’s part number.; Always make sure there is no pressure in the system prior to removing a PRV.

These instructions are divided into two sections: 1” Body and 2” Body.

1. Cut and remove the seal wire and unscrew the cap to expose the adjustment screw.

i) Go to "c" if the valve is a lift lever configuration.

2. Loosen the lock nut from the adjustment screw.

3. Relieve the compression on the spring by turning the adjustment screw counter clockwise.; This is important so that components will not spring out and pose a hazard.; If the adjustment screw begins to appear as residing back into the bonnet during the relieving of the preload, then the spring compression has been completely removed and the adjustment bushing is beginning to re-compress the spring.

4. Rigidly support the body to prevent movement during disassembly.

5. Unscrew the inlet base using the appropriate wrenching flats.; 6. Remove the set spring and discard the disk subassembly.

The following general procedure is recommended for the inspection of an 8100 Series PRV.

New parts should be inspected.

1. Inspect the seat for cuts and abrasions. The seat is the non-metallic element in the nozzle subassembly.

a) If there are only minor scratches or abrasions, the seat may be polished and restored.

b) Polish the seat area lightly with a fine grade abrasive pad. Be careful not to damage the soft seat.

c) If the seat is damaged with deep abrasions and cuts, it should be replaced.

2. Referring to Figure 29, measure the diameter Ds of the nozzle. This diameter must be in the range of values listed in Table

ORIFICE SIZE - ½", NOZZLE DIAMETER Ds, in (mm), 0.620 (15.75) - MINIMUM, 0.622 (15.80) - MAXIMUM

ORIFICE SIZE -¾", NOZZLE DIAMETER Ds, in (mm) 0.914 (23.22) - MINIMUM, 0.916 (23.27) - MAXIMUM

Warning: This procedure requires trained personnel with PPE!

Enter the pressure losses to the gauges

Warning: This procedure requires trained personnel with PPE!

If system is not operational, report the issues to the maintenance team and stop the procedure

Are the block valves under the valve functioning properly?

Enter the pressure reading from the gauge

If the gauge is placed too far away from the valve or the line has too many restrictions, there will be pressure loss.

Is there a heavy warn or simmer causing false readings?

If yes, adjust the test volume and retest.

Is the supply pressure sufficient for the test?